Method for measuring uniformity of tires

Abstract

Tire uniformity measuring method wherein imbalanced forces are measured and then removed from the final forces produced by a high-speed tire to give a final readout of forces which are the true dynamic road wheel contact forces on a tire under load.

I claim: 
     
       1. A method of determining the uniformity of wheels comprising the steps of mounting a wheel on a rotatable rim, rotating said wheel to a predetermined speed, measuring the imbalance forces on said wheel without load thereon, thence rotating said wheel at said predetermined speed under a predetermined load, measuring the force variance on said wheel under said predetermined load and speed, subtracting said imbalance forces from said force variance to give a resultant contact force. 
     
     
       2. A method of determining the uniformity of wheels as set forth in claim 1 wherein said predetermined speed can be in a range from 35 miles per hour to 100 miles per hour. 
     
     
       3. A method of determining the uniformity of a rotary body comprising the steps of rotating said body at a predetermined speed, measuring the incremental imbalance forces on said tire as a function of one revolution of said body to give a first signal, thence rotating said body at said predetermined speed and at a predetermined load thereon, measuring the force variance incrementally on said body as a function of one revolution of said body to give a second signal that is in synchronism with said first signal, and subtracting said first signal from said second signal to give a resultant dynamic contact force measurement for said wheel that represents the road contact forces on said rotary body under load. 
     
     
       4. A method of determining the uniformity of said rotary body as set forth in claim 3 wherein said predetermined speed is above five miles per hour. 
     
     
       5. A method of determining the uniformity of said rotary body as set forth in claim 4 wherein said imbalance force is a nonlinear force due to centrifugal force of imbalance as a function of time. 
     
     
       6. A method of determining the uniformity of said rotary body as set forth in claim 5 wherein said predetermined load is above one thousand pounds. 
     
     
       7. A method of determining the uniformity of a rotary body comprising the steps of: rotating said body at a predetermined speed without load; producing by strain gauges coupled to said rotary body a first signal having an amplitude which varies as a function of the imbalance in said rotary body; rotating said body at said predetermined speed and at a predetermined load; in synchronism with the speed and location of said first signal; producing by strain gauges coupled to said rotary body a second signal having an amplitude which varies as a function of the force variance of said rotating body; and subtracting said first signal from said second signal to give a resultant contact force that reflects the true nonuniformity forces of said rotating body as it traverses the road surface. 
     
     
       8. A method of determining the uniformity of a rotary body as set forth in claim 7 wherein said first and second signals are in synchronism to reflect the corresponding locations on said rotary body. 
     
     
       9. A method of determining the uniformity of a rotary body as set forth in claim 8 wherein each of said signals is taken over one full revolution of said rotating body.